Multicolor diazotype layers



Patented Feb. 20, 1951 MULTICOLQR DIAZOTYPE LAYERS Sam Charles Slifkin, Binghamton, N. Y., asslgnor to General Aniline & Film Corporation, New York, N. Y., a corporation of Delaware No Drawing. Application December 5, 1947, Serial No. 790,026. In Great Britain July 16, 1945 Claims. 1

This invention relates to diazotype light sensitive media. More particularly, it relates to that type of diazotype reproduction media wherein the positive copies obtained from the exposure of the reproduction media under a positive original is developed in the dry state by contact with a gaseous developing agent. This application is a continuation-in-part of my copending application Serial No. 545,201, filed July 15, 1944, now abandoned.

Diazotypes of this class are generally produced by treating the surface of a suitable base such as paper, cellulose acetate film, cellophane, glass and metal surfaces with a solution of two dye components, one of which, the diazo compound, is the photosensitive body and the other, the azo component or coupling component, is a compound capable of reacting under suitable condi-,---

under an original tracing, design or printed sheet to a proper source of light, the diazo compound, in those areas which are not protected by the solid lines of the tracing or design or letters of the printed sheet, is decomposed. Upon subsequent development, a dye forms only in the areas which were protected from the light by the said lines of the tracing, design or letters of the printed sheet and thus the original is reproduced in the color called for by the particular combination of a diazo compound and coupling component present in the light sensitive layer. In cases where there is a distinct variation in the densities of various parts of the original which is to be copied, such as where there are ink lines and pencil marks or pencil lines on the same original drawing or where there are shadows and high-lights on a design, the lines of weaker density, half-tones or h gh-lights will appear, if at all, as indistinct or dispersed shades of the same color tone as the full densities or shadows. In many cases where the contrast between the full 2 densities and the half-tones or high-lights of the original is very great, no reproduction of the half-tones or high-lights will be obtained since the degree of exposure necessary to decompose the diazo compound in the background areas will also completely or almost completely decompose the diazo compound in the half-tone or highlight areas.

It has now been discovered that the full densities or shadows and the half-tones or high-' lights of an original can be reproduced in different colors, thus indicating the existing dif-' ference in densities without the necessity of, creating such a low density in the reproduction of the half-tones or high-lights as to render them indistinct. This effect is produced by adding to the light sensitive coating solution a number of coupling components differing widely from each other in their coupling rates or potentials and forming contrasting colors when coupled with the diazo compound.

It has'been observed that the rate of formation of an azo dye is dependent upon many variables but is in large part predetermined by the inherent nature of the dlazonium compound and the coupler or couplers used in the formation of the azo dye. Thus, under identical conditions, a single diazo compound will couple at greatly varying rates with a series of different azo components or couplers and a, single coupling component will also couple at greatly varying rates with a series of different .diazo compounds. Thus, in the selection of diazo compounds and couplers for the production of a diazotype light sensitive layer, the combination of a slow coupling diazo and a. fast coupling azo component will be similar in eifect to a fast coupling diazo and a slow coupling azo component. This effect produced by the inherent properties of the diazo compound and coupling component is referred to as the coupling potential and wherever that term is used throughout this specification and appended claims, it will be understood therefore to mean the coupling time-relation between a given diazo compound and a given coupling component.

This variation in the coupling potentials in a diazotype system containing a single diazo compound and two or more coupling components is the controlling factor in the selectivity of the diazo for the coupler determining the color of a given density area. The relative concentration of the coupling components is also a contributing factor. Thus, concentration can be used to offset the unfair competition of the more energetic coupier having a higher coupling potential. In areas where there is a high concentration of diazo the coupler of high coupling potential will be used up first.- Then coupling will take place with the less energetic coupler. By limiting the concentration of the high potential coupler the color produced by the slow coupler will predominate in such areas of high diazo concentration.

When using a continuous tone or multidensity original the concentration of the light sensitive diazo is varied by exposure to light of a diazotype under such an original so that a series of diflerent concentrationsof diazo are produced on the irradiated sheet. The concentration of the couplers in a two-component diazotype system will'remain the same throughout. In each density area of the exposed diazotype then will be competitive coupling controlled by the coupling potentials and relative concentrations of the couplers. By using a relatively high concentration of the slower coupler and a relatively small amount of the fast coupler, coupling will be controlled by the energetic coupler only in the areas where there is a low concentration of the diazo. The diazo in those areas will become exhausted by the energetic coupler before the slow coupler has an opportunity to exert its influence. As the concentration of the diazo increases in the half-tone areas, where there is not enough of the energetic coupler to combine with all of the residual diazo, more and more of the slow coupler will react until in the high density areas the slow coupler exerts its influence on the color produced to its fullest extent. Any color produced by the energetic or fast coupler in such areas will be completely overshadowed 'by the color of the slow coupler,

In order to obtain optimum contrast between the high density and low density areas it is preferable to not only react a combination of energetic and slow couplers which will produce 45 contrasting colors with the diazo compound, but to combine the couplers in such a molar ratio to each other that the slow coupler will be in considerable excess. The exact ratio will depend upon the tinctorial strength of the color produced by the slow coupler, there being suflicient of the more active or energetic coupler present to prevent any appreciable degree of coupling by the slow coupler in the half-tones or highlight areas. Ratios of from to /40 in favor 55 4 from the following examples which are illustrative of the invention but are not intended to limit in any way the scope thereof. The parts are by weight unless otherwise specified.

Example I A coating solution is prepared by slowly mixing the following ingredients in the proportions given at room temperature:

above solution in the usual manner by employing a doctor blade to remove the excess solution and the thus coated paper is then dried. Samples of this coated paper may then be exposed to light under a diapositive containing full density and half-tone areas and the thus exposed sensitized samples developed in the usual manner by contacting the sensitized side of the paper with a mixture of water vapor and ammonia gas. The

full density areas of the original will be reproduced in a green tone and the half-tone or low density areas will be reproduced in a purple tone. If 2 grams of the m-hydroxy phenylurea coupler instead of 1 gram are used in the coating solution of this example, the reproduction in the full density areas will be in a yellow-green tone and that in the lower density areas in a bluish-black tone.

Example II A coating solution is prepared by slowly mixing the following ingredients in the proportions given at room temperature:

Water PP Glycerin 5 Citric acid g-.. 10 Zinc chloride g 5 'I'hiourea g 5 2,3-dihydroxy naphthalene g 0.05 7-hydroxy-1,2-naphthimidazol g 1 p-Diazo-N-diethyl aniline ZnClz double salt g 3 A diazotype stock paper is coated with the half-tone areas and the thus exposed samples ethoxyaniline; p-diazo-N-ethyl-N-ethoxyaniline;

1-diazo-3-methyl-4-N-ethylaminobenzene; and 1 diazo 3 methoxy-4 N cyclohexylaminobenzene. These diazo compounds are preferably used in the form of their double salt complexes,

such as the zinc chloride double salt, the

cadmium chloride double salt; the chlorobenzenesuifonate, the tin chloride double salt, the borofluoride and the sulfate of the diazo compound.

This invention will be more fully understood developed by contacting the sensitized side of the paper with a mixture of water vapor and ammonia gas. The full density areas of the original will be reproduced in a red tone and the halftone or low density areas will be reproduced in a blue tone. If gram of the 7-hydroxy-1,2- naphthimidazol coupler is used instead of 1 gram in the coating solution of this example, the full density areas will be reproduced in a red-purple tone and the low density areas in a blue tone.

The following table provides further combinations of slow and fast couplers which will give contrasting colors with the diazo compound, it being understood that the coating composition is prepared in the same manner as given above in Examples I and II, the slow coupler being always used in excess ratio over the last coupler.

areas oi an original in contrasting colors which comprises in combination a mono-diam deriva- Diazo Compound Slow Coupler Fast Coupler 5g; g: 3: Low

p-diazo-diphenyl-amine. m-hydroxy-acetanilide 2,3-dihgdroxy-nsphthalene Green Blue. p-diazo-N-diethyl aniline 7-hydroxy-naphthalene-l,2- 1,8lhdfi ydroxy-naphthalene- Red Do.

imidazole. m-bydroxy-phenylurea p-diazo-diphenyl-amine 7-hyd rainy-naphthalene l ,2-

onic acid. 2,3-digzdroxynaphthalene Purple. Blue p-diazo-N-diethyl aniline imidazole.

2-h droxy-s-naphthoic acid (etheuediamine amide). 7- ydroxy-naphthalene-lbiguanide.

phenylmethyl pyrazolone OrclnoI Having now particularly set forth and described my invention and having illustrated the best method of performing it, what I now claim as new 1. A diazotype light sensitive layer for the reproduction of different photographic density areas of an original in contrasting colors which comprises in combination a monodiazo derivative of a p-diamine of the benzene series and sisting of m-hydroxyacetanilide, m-hydroxy-;

phenylurea,

ene-l-biguanide, the said slow coupling component being so selected as to produce with thediazo compound a different color tone than'i's produced by combination of the diazo compound with the fast coupling component.

2. A diazotype light sensitive layer for the reproduction of different photographic density areas of an original in contrasting colors which com; .prises in combination a monodiazo derivative or. a p-diamine of the benzene and, in the ratio from 20/1 to 40/1 by weight, m-hydroxyphenylurea, and

2,3-dihydroxynaphthalene.

3. A diazotype light sensitive layer for the reproduction of different photographic density areas of an original in contrasting colors which comprises in combination p-diazo-diphenylamine, and, in the ratio of 20/1 by weight, m-hydroxy phenylurea, and 2,3-dihydroxynaphthalene. 1

4. A diazotype light sensitive layer for the reproduction of different photographic density 7-hydroxynaphthalene-1,2-imidazole, ethylenediamine amide of 2-hydroxy-3-hy-" droxy-3-naphthoic acid and 'I-hydroxynaphthal-i Red.

Bed/Brown.

tive of a p-diamine oi the benzene series and, in the ratio from 10/1 to 20/1 by weight, 7-hydroxynaphthalene-1,2-imidazol, and 2,3-dihydroxynaphthalene.

5. A diazotype light sensitive layer for the reproduction of diflerent photographic density area's of an original in contrasting colors which com prises in combination p-diazo-N-diethylaniline and. in the ratio of 20/1 by weight, 7-hydr0Xynaphthalene-lfi-imidazol, and 2,3-dihydroxynaphthalene.

SAM CHARLES SLIFKIN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,760,780 Schmidt et al May 27, 1930 1,845,989 Schmidt et al '1"eb. 16, 1932 1,966,755 D'Hauterine July 1'7, 1934 1,967,351 Schmidt et a1 July 24, 1934 1,989,065 Schmidt et al. Jan. 22, 1985 2,034,508 De Boer et al Mar. 1'', 1936 2,037,542 Schmidt et a1 Apr. 14, 1930 2,095,408 De Boer et a1 Oct. 12, 193'] 2,150,565 Schmidt et al Mar. 14, 1939 2,157,206 Hinman May 9, 1939 2,381,984 Reichel Aug. 14, 1945 FOREIGN PATENTS Number Country Date 880,087 France Feb. 19. 1929 OTHER REFERENCES Spencer: Photographic Application of Diazo Compounds," The Photographic Journal, London, Dec. 192a. @1490 to 490. 

1. A DIAZOTYPE LIGHT SENSITIVE LAYER FOR THE REPRODUCTION OF DIFFERENT PHOTGRAPHIC DENSITY AREAS OF AN ORIGINAL IN CONTRASTING COLORS WHICH COMPRISES IN COMBINATION A MONODIAZO DERIVATIVE OF A P-DIAMINE OF THE BENZENE SERIES AND, IN THE RATIO OF FROM 1/10 TO 1/40 BY WEIGHT, A FAST COUPLING COMPONENT SELECTED FROM THE GROUP CONSISTING OF 2,3-DIHYDROXYNAPHTHALENE, 1,8-DIHYDROXYNAPHTHALENE-4-SULFONIC ACID, PHENYLMETHYL PYRAZOLENE AND ORCINOL AND A SLOW COUPLING COMPONENT SELECTED FROM THE GROUP CONSISTING OF M-HYDROXYACETANILIDE, M-HYDROXYPHENYLUREA, 7-HYDROXYNAPHTHALENE-1,2-IMIDAZOLE, ETHYLENEDIAMINE AMIDE OF 2-HYDROXY-3-HYDROXY-3-NAPHTHOIC ACID AND 7-HYDROXYNAPHTIALENE-1-BIGUANIDE, THE SAID SLOW COUPLING COMPONENT BEING SO SELECTED AS TO PRODUCE WITH THE DIAZO COMPOUND A DIFFERENT COLOR THE DIAZO COMPOUND PRODUCED BY COMBINATION OF THE DIAZO COMPOUND WITH THE FAST COUPLING COMPONENT. 